Nobuhiro Umemura

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K2Al2B2O7 has been found to be phase matchable for type-1 sum-frequency generation (SFG) at 0.193 microm by mixing the Nd:YAG laser wavelength at 1.0642 microm and the SFG output of the RbTiOAsO4 optical parametric oscillator tuned at 0.2358 microm. An average power of 200 mW at 10 kHz was obtained in a 7-mm-long crystal. In addition, the Sellmeier(More)
This paper reports high-accuracy Sellmeier and thermo-optic dispersion formulas for GaSe that provide excellent reproduction of the phase-matching conditions for second-, third-, and fourth- harmonic generation of CO2 laser radiation at 10.5910 μm in the 20°C-200°C range as well as the data points of Feng et al. [Opt. Express16, 9978(More)
The Sellmeier equations for GaS and GaSe are constructed from the nonlinear experiments thus far reported in the literature. The model calculations based on these equations were found to reproduce well the phase-matching conditions for second-harmonic generation of the Er:YSGG laser at 2.7960 μm and the CO2 laser lines at 9.5862 and 10.5910 μm achieved in(More)
Femtosecond time-resolved mid-infrared (MIR) spectroscopy based on chirped-pulse upconversion is a promising method for observing molecular vibrational dynamics. A quantitative study on nonlinear media for upconversion is still essential for wide applications, particularly at the frequencies below 2000  cm<sup>-1</sup>. We evaluate wide-bandgap nonlinear(More)
GdCa4O(BO3)3 has been found to have phase-matching points where the temperature variations of the phase-matching angles become zero for type-1 sum-frequency generation in the zx plane. We also found that the temperature sensitivities of the phase-matching conditions in the zx plane are different along the phi = 0 degrees and phi = 180 degrees directions in(More)
Third-harmonic generation (THG) has been investigated in the monoclinic BiB(3)O(6). The symmetry and birefringence analysis revealed that there are phase-matching conditions for the direct third-order nonlinear process, where the cascading second-order processes are precluded by the zero effective nonlinearity. The first phase-matched pure chi((3)) THG in a(More)
We report new experimental results on the phase-matching properties of yellow color HgGa<sub>2</sub>S<sub>4</sub> crystals for harmonic generation of an Nd:YAG laser-pumped KTiOPO<sub>4</sub> (KTP) optical parametric oscillator (OPO) and CO<sub>2</sub> lasers in the 0.944-10.5910 μm range. In addition, we present new Sellmeier equations that provide a good(More)
BiB3O6 has been found to be simultaneously phase matchable for sum-frequency generation at 0.4627 and 0.6260 microm by mixing the outputs of a 0.5321 microm pumped parametric oscillator with the fundamental source at 1.0642 microm. The simultaneous blue and red light generation is achieved under the temperature-insensitive phase-matching condition, and the(More)